OLLO Audio S4X
OLLO Audio S4X
OLLO Audio S4X

OLLO Audio S4X: Perfectly calibrated headphones for mixing

OLLO,has unveiled its latest innovation: the Audio S4X open full-size headphones. These cutting-edge headphones follows in the footsteps of its predecessor, the Audio S4R closed model, which garnered acclaim upon its recent release.

Crafted with meticulous attention to detail, the Audio S4X boasts a robust stainless steel headband, exquisitely fashioned American walnut cups, and luxuriously comfortable leather and velour ear pads. Delivering an unparalleled auditory experience are the 50 mm speakers meticulously engineered within.

Designed with professionals in mind, these headphones are recommended for tasks such as mixing and mastering, where precision and clarity are paramount. Operating within a frequency range spanning from 20 Hz to 20,000 Hz and achieving a maximum sound pressure of 102 dB, the Audio S4X ensures an immersive listening experience with every use, backed by an impedance of 32 Ohms.

Adding to its versatility, the device comes equipped with a calibration plugin (USC) tailored for compatibility with personal computers running Windows and Mac operating systems, supporting AU and VST3 formats. Furthermore, users can expand their audio toolkit with the Waves NX plugin, enabling dynamic room modeling capabilities.

The Audio S4X is now available for purchase, offering an exceptional value proposition at a price point of $450. Included in the package is a detachable cable featuring an adapter to Jack 6.3 mm, ensuring seamless connectivity across a range of devices and applications.


Studio reference class, open back, dynamic headphones with flat frequency response and USC calibration.


  • Hand-picked and left / right matched transducers delivering accuracy and instrument separation. (+/-1dB SPL tolerance, pink noise, range 100Hz-10kHz in free field)
  • 50 mm, PET 25u membrane, 2-layered coil, 32 ohms,
  • Dynamic Neodymium speaker with 109dBSPL (S4X) / 111dBSPL (S4R) 1Vrms@1KHz 30ohm output that makes them work with smart devices too.
  • Replaceable using home tools.


  • Replaceable earpads with an outer diameter of 90 mm(3.5inch), an inner diameter of 55mm(2.2inch) and a depth of 20mm(0.8inch).
  • Hybrid artificial leather and velour earpads to control flow resistance around the earpads seal resulting in smoother response in low mids and mids (150Hz-1kHz) perceived as natural timbre on vocals, pianos, strings,…
  • 1kHz @ 85dBSPL sweep THD < 0.084%S4X / 0.079%S4R , Variation in frequency response in band from 20Hz to 20kHz ~13,7 dB SPL S4X / 10,0dB SPL S4R, pink noise IEC 60318-1 compatible standard.
  • Fully separated front and back of the speaker for minimal phase cancellation and a more direct sound signature. SoundSeal™


  • Self-adjusting artificial leather strap
  • Clamping force set for most neutral frequency response on industry-standard bitragional diameter of 14.3cm (KEMAR)
  • Stainless spring steel powder coated
  • 360 earcups rotation
  • Strap and steel are replaceable using home tools


  • Detachable braided silicone cable employing OFC core to ensure minimal signal distortion.
  • Colour labelled L and R (Left is Black)
  • Reversible to have the cable coming down behind your back when playing an instrument or in front when producing with a desktop interface.